Inelastic Response of Plan-Irregular Structures under Multi-Component Earthquake Excitations

Torsional behavior due to asymmetric plan distributions of mass, stiffness and/or strength has been recognized as one of the major sources of structural damage and of failure during strong earthquakes. This paper is aimed at showing how torsional behaviour may affect response of buildings and of industrial facilities to earthquake excitations by analyzing a simple one-storey asymmetric model and by comparing its displacement response to that obtained from a reference symmetric system, i.e. an equivalent system with no torsional behaviour. A further investigation is carried out in order to define influence of different modeling assumptions - namely capability to account for interaction phenomena in the inelastic range of behaviour - and of vertical input ground motions on amplifications in displacement response of plan-irregular structures.